Temporal analysis of the diet of the central rock-rat

Abstract

The central rock-rat (Zyzomys pedunculatus) is an endangered endemic rodent that has undergone a dramatic range contraction over the past century. It is currently known from only a small area of the West MacDonnell Ranges near Alice Springs. A previous investigation into the species’ diet that analysed a small number of faecal samples concluded tentatively that it was a granivore. The present study aimed to establish the dietary patterns of Z. pedunculatus across a two-year period in central Australia during which rainfall fluctuated markedly. Diet was determined through the microscopic analysis of material in faecal pellets of Z. pedunculatus trapped at approximately three-month intervals at five sites at Ormiston Gorge. Seed was found to be the most important dietary item, comprising on average 57.0% of the diet across sample periods. Under dry conditions, the amount of seed material in the diet declined and the amount of stem material increased. Plant material from 15 genera was recorded in the diet, most notably Sida spp., Solanum spp. and Triodia brizoides. All of the plant genera identified in the diet to date are widespread and common in the range country of central Australia and most are considered fire tolerant. On the basis that the diet contains more than 50% seeds, Z. pedunculatus can be described as a granivore. However, the diet is broad and includes both seeds and vegetative material from a range of plant species.